The present invention relates to a process for recovering a finished oil product from contaminated or crude waste oils, and apparatus for carrying out the process. In particular, the present process calls for introducing vapors which are produced from heating of the waste oil in a tank by a gas or oil fired flame, back into the flame so that light ends included in the vapors are combusted by the flame to provide additional heat for heating the waste oil in the tank. The present apparatus includes burner means for heating the waste oil in the tank, together with suitable afterburner means for combusting the vapors with the flame provided by the burner means.
It is known to recycle vapors produced when crude oil is heated by a furnace, back through a heat exchanger wherein the heat of the vapors is transferred to an incoming crude oil stream for purposes of preheating the stream. Such an arrangement is disclosed in U.S. Pat. No. 4,321,132 issued Mar. 23, 1982. In the system of U.S. Pat. No. 4,321,132, however, a main furnace-heater is provided for elevating the temperature of the crude oil stream to about 600.degree. F., and a separate flash separator is provided for dividing the heated stream into a vapor portion and a fluid portion. As mentioned, the vapor portion is routed through a separate heat exchanger to preheat the incoming crude oil stream. From the heat exchanger, the vapor portion is then conducted to a fractionation column. U.S. Pat. No. 4,292,140, issued Sept. 29, 1981, relates to a distillation process in which heats of distillates and bottom products are recovered by heat exchangers so as to preheat a main feed, and the heat of the distillates is transferred to boiler water to generate steam. According to the patent, the steam can be used to atomize fuel which fires a heating furnace, and may also be injected into the main feed line in the heating furnace to increse the flow of feed charged into the distillation column.
The known conventional waste oil recovery processes fail, however, to utilize efficiently all the heat which may be obtained from the vapors produced upon heating of the waste oil, for preheating or supplemental heating of the waste oil in a recovery system.